The present invention relates to a method for manufacturing a transparent capsule, and in particular, relates to a method for manufacturing an almost spherical body comprising transparent resin such as acrylic resin or the like.
The present applicant has previously proposed in various ways a sun's ray collecting device in which the sun's rays are focused on a lens, guided into an optical conductor, and then transmitted through the optical conductor onto an optional desired place for use in illumination or for other like purposes. Furthermore, the present applicant has also proposed that the afore-mentioned sun's ray collecting device be accommodated in a transparent capsule in order to protect the lens thereof from wind, rain, dust and so on.
The sun's ray collecting device previously proposed by the present applicant has a cylindrical foundation, a dome-shaped head portion made of a transparent body, and a capsule for use in the sun's ray collecting device constructed with the foundation and the head portion. When the device is employed, the sun's ray collecting device is accommodated in the capsule. The sun's ray collecting device comprises, for instance, a large number of lenses, or a parabolic light collector, or a reflex mirror, etc. The sun's rays focused by the lenses or the parabolic light collector are guided into the optical conductor cable. Otherwise, the sun's rays reflected on the reflex mirror are guided into the photo-conductive tube or the like. The sun's rays guided in such a way are transmitted through the optical conductor cable or the photo-conductive tube onto an optional desired place.
And further, in the sun's ray collection device as mentioned above, the above-mentioned transparent capsule is usually made of acrylic resin. However, since the transparent capsule is employed for guiding the sun's rays thereinto, it is necessary to provide a fine polishing on the surface of the capsule in order to create a mirror-like surface for the purpose of reducing the loss of light transmission, due to diffused reflection, etc. and to make uniform the quality of the entire capsule in order to cause the light rays guided into the capsule to effectively propagate toward the lenses, the parabolic light collector, or the reflect mirror. However, when the transparent capsule is manufactured through the use of injection-molding or compression-molding methods, it is difficult to polish the surface thereof into a mirror and provide a proper finish to the capsule in order to make its quality uniform. It also makes it difficult to manufacture such a capsule at low cost.
Furthermore, when the capsule is manufactured by the use of the blow-molding method, it is difficult to make its' thickness uniform. And further, it is also difficult to create an almost completely spherical body, so that the capsule manufactured in the way just mentioned lacks a uniform quality.